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Abstract
Quantum calculations study the potential of an intramolecular H-bond between the halogen atom (X) of a halobenzene and a substituent placed ortho to it, to amplify the ability of X to engage in a halogen bond (XB) with a Lewis base. H-bonding substituents NH2, CH2CH2OH, CH2OH, OH, and COOH were added to halobenzenes (X = Cl, Br, I). The amino group had little effect, but those containing OH increased the CX···N XB energy to a NH3 nucleophile by about 0.5 kcal/mol; the increment associated with COOH is larger, nearly 2 kcal/mol. These energy increments were approximately doubled if two such H-bonding substituents are present. Combining a pair of ortho COOH groups with an electron-withdrawing NO2 group in the para position has a particularly large effect, raising the XB energy by about 4 kcal/mol, which can amount to as much as a 4-fold magnification.
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Affiliation(s)
- Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
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2
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Scheiner S. Ability of Peripheral H Bonds to Strengthen a Halogen Bond. J Phys Chem A 2022; 126:9691-9698. [PMID: 36520542 DOI: 10.1021/acs.jpca.2c07611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Quantum calculations study the manner in which the involvement of a halogen atom as a proton acceptor in one or more H bonds (HBs) affects the strength of the halogen bond (XB) it can form with a nucleophile aligned with the X σ-hole. A variety of Lewis acids wherein X = F, Cl, Br, and I are attached to a tetrel atom C or Ge engaged in a XB with nucleophile NH3. One, two, and three HF molecules were positioned perpendicular to the XB axis so that they could form a HB to the X atom. Each such HB strengthened the XB by an increment of 1 kcal/mol or more that does not attenuate as each new HB is added, potentially increasing the interaction energy manyfold. Additionally, the presence of one or more HBs facilitates the formation of a XB by molecules which are reluctant to engage in such a bond in the absence of these auxiliary interactions. Even the F atom, which avoids such a XB, can be coaxed to participate in a XB of moderate strength by one or more of these external HBs.
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Affiliation(s)
- Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States
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3
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Zhao C, Wang Y, Shi B, Li M, Yan W, Yang H. Domination of H-Bond Interactions in the Solvent-Triggering Gelation Process. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:7965-7975. [PMID: 35731623 DOI: 10.1021/acs.langmuir.2c00677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Gels prepared with the solvent-triggering method are attractive for their easy and fast preparation; however, the role of solvents in this process remains unclear, which hinders the efficient and accurate control of desired gel properties. In this study, the role of solvents in the solvent-triggering gelation process is studied using 9-fluorenylmethoxycarbonyl (Fmoc)-protected diphenylalanine (Fmoc-FF) as the gelator. Density functional theory (DFT)-based calculations and corresponding wavefunction analyses are conducted to identify the H-bonding interaction sites between the molecules. The calculation results clearly annotate the activating role of DMF and the triggering role of H2O in the gelation process. The solvation of Fmoc-FF by DMF can activate the H-bonding sites on the peptide chain, showing a conformation reversal and higher electrostatic potentials. Then, the H-bonding between Fmoc-FF and H2O is facilitated to trigger gelation. The physical Fmoc-FF/DMF/H2O gels show easily tuned mechanical strengths (G' of 102-105 Pa), injectable potentials (general yield strain < 100%), and stable recoverability (80-98% within 100 s). The regulation of these properties depends on not only the gelator concentration but also the H-bonding interactions with solvent molecules, which have seldom been studied in detail before. By understanding the effect of solvents, low-molecular-weight gelator-based gels can be designed, prepared, and tuned efficiently for potential applications.
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Affiliation(s)
- Chengcheng Zhao
- State Key Laboratory of Multiphase Flow in Power Engineering, Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yanyao Wang
- State Key Laboratory of Multiphase Flow in Power Engineering, Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Bofang Shi
- State Key Laboratory of Multiphase Flow in Power Engineering, Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Mingtao Li
- State Key Laboratory of Multiphase Flow in Power Engineering, Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Wei Yan
- State Key Laboratory of Multiphase Flow in Power Engineering, Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Honghui Yang
- Xi'an Key Laboratory of Sustainable Energy Materials Chemistry, Department of Applied Chemistry, Xi'an Jiaotong University, Xi'an 710049, China
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Basharat M, Shah ZH, Ikram M, Ghellab SE, Hassan QU, Ilyas T, Lei L, Lin G, Gao Y. Inorganic-Organic Hybrid Copolymeric Colloids as Multicolor Emission, Fuel-Free, UV- and Visible-Light-Actuated Micropumps. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2107621. [PMID: 35142080 DOI: 10.1002/smll.202107621] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/28/2022] [Indexed: 06/14/2023]
Abstract
Light-actuated micromachines are of enormous interest due to their ability to harvest light for triggering catalytic reactions to acquire free energy for mechanical work. This work presents an inorganic-organic hybrid copolymeric poly(cyclotriphosphazene-co-barbituric acid) colloid, which displays multiwavelength excited emission and catalytic activities, exploiting the unique structural, chemical, and optical features of inorganic heterocyclic ring hexachlorocyclotriphosphazene and organic co-monomer barbituric acid. Specifically, this work reveals particle-resolved unusual multicolor emission under excitation with the same or different wavelengths of light using fluorescence microscopy. The result is rationalized by density functional theory studies. In this work, the authors find that emission is coincident with fluorometric measurements, and the photocatalytic properties are anticipated from the overall band structure. This work also demonstrates the use of these colloids as micropumps, which can be remotely activated by UV, blue, and green lights under fuel-free conditions, and ascribe the behavior to ionic diffusiophoresis arising from light-triggered generation of H+ and other charged species. This work offers a new class of polymeric colloids with multiple-wavelength excited emission and catalytic activities, which is expected to open new opportunities in the design of fuel-free, photo-actuated micromachines and active systems.
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Affiliation(s)
- Majid Basharat
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Zameer Hussain Shah
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
| | - Muhammad Ikram
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Salah Eddine Ghellab
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Qadeer-Ul Hassan
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Tayiba Ilyas
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Lijie Lei
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Guanhua Lin
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
| | - Yongxiang Gao
- Institute for Advanced Study, Shenzhen University, Nanhai Avenue 3688, Shenzhen, 518060, P. R. China
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6
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Characterization of orthogonal hydrogen and halogen bonds in thiobarbituric acid complexes with halogen molecules (X =
I
2
, Br
2
, and Cl
2
): Structural and spectroscopic study. J CHIN CHEM SOC-TAIP 2021. [DOI: 10.1002/jccs.202100101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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